The present invention is in the field of diagnostic kits. More particularly, the present invention is directed to diagnostic kits for detection of hemoglobin, myoglobin, ferritin, or the like substances having peroxidase-like activity in different mixtures of biological origin, such as fecal blood in a toilet bowl, occult blood in the breath of bleeding horses, or myoglobin present in the urine of severely muscle damaged victims.
Techniques based on a visually observable color reaction for detecting the presence of occult blood in biological specimens, such as human feces and urine, have been known for a long time in the clinical diagnostic and related arts.
A basic description of such a test for occult blood is given, for example, in the book 37 A SYLLABUS OF LABORATORY EXAMINATIONS IN CLINICAL DIAGNOSIS", Harvard University Press, Cambridge, Mass., 1966, L. B. Page and P. J. Culver, Editors, pages 377-478.
Briefly, this well known test takes advantage of the peroxidase activity of hemoglobin, whereby hemoglobin catalyzes the decomposition of hydrogen peroxide (H.sub.2 O.sub.2), or of several other peroxide compounds into water and 37 nascent" oxygen (37 O"). The resulting "nascent" oxygen reacts with gum guaiac, containing phenol guaiacetic acid giving rise to a colored dye reaction product having a quinone-type structure. In its simplest form, described, for example, in the above-noted reference book, a small sample of the stool to be tested is applied to the filter paper and a few drops of glacial acetic acid, of saturated ethanolic gum guaiac solution, and of three percent (3%) aqueous hydrogen peroxide solution, are added. The appearance of a blue or bluish green color indicates the presence of peroxidase-like activity, and, therefore, the presence of occult blood in the stool sample.
Many variations of the above-summarized basic test procedure, in terms of the chemicals and/or apparatus employed, were developed in the art, as is apparent from the following patents and other references: U.S. Pat. No. 4,427,769; U.S. Pat. No. 4,092,120; U.S. Pat. No. 4,472,498; U.S. Pat. No. 4,016,043; U.S. Pat. No. 4,436,823; U.S. Pat. No. 4,333,734; "Spectrophotometry of Occult Blood In Feces", Clin-Chem 1983, Dec. 29(12), pages 2022-2025, by C. L. Welch, et al.; "Occult Fecal Blood Loss Determined By Chemical Tests and A 51 Cr Method", Scand. Journal of Gastroenterology, 1981, 16(2), pages 245-252, by J. H. Dybdahl, et al.; "A New Occult Blood Test Not Subject To False-Negative Results from Reducing Substances", J. Lab. Clin. Med., 1979, May 93(5), pages 879-886, by R. M. Jaffe, et al.; "HemoQuant, A New Quantitative Assay For Fecal Hemoglobin", Ann. Intern. Med., 1984, September 101(3), pages 297-302, by D. A. Ahiquist, et al.; "Detection of Occult Blood In Gastric Juice", Journal of Clinical Gastroenterology, 1984, April 6(2), pages 119-121, by P. Rosenthal, et al.; "Screening For Colorectal Cancer Using Guaiac Slide Test", the Hemocult II Stool Guaiac Slide Test", Cancer, 1984, May 53(10), pages 2201-2205, by K. M. Cummings, et al.; "The Use of Hemocult Test For Detection of Blood In Gastric Aspirates", Scand. Journal of Gastroenterology, 1983, 18(6), pages 723-727, by M. Starlinger, et al.; "The Hemo-matic Analyzer: A New Occult Blood Testing Device", American Journal of Gastroenterology, 1984, February 79(2), pages 117-121, by D. Y. Graham, et al.; "The Early Detection of Colorectal Cancer", Cancer, 1977, August 40(2), pages 945-949, by S. F. Miller, et al.; "Reliability of Chemical Tests For Fecal Occult Blood In Hospitalized Patients", American Journal of Digestive Diseases, October, 1976, 21(10), pages 845- 852, by D. W. Morris, et al.; and "Tests For Occult Blood In Stools of Children", Arch. Dis. Child., March, 1975, 50(3), pages 238-240, by A. E. Ford-Jones, et al.
As the above-cited references demonstrate, testing for occult blood in human stool samples provides a very significant aid to the early detection, and therefore early treatment of colorectal cancer
In addition to gum guaiac, other chromogenic substances have also been used in the prior art to provide a visually observable colored dye to indicate the presence of occult blood (or better stated, peroxidase activity) in stool samples and other biological specimens. These chromogens include, for example, orthotolidine, phenolphthalein, and tetramethylbenzidine, although gum guaiac still appears to be the chromogen employed in most tests.
One problem which arises in connection with the occult blood tests of the prior art relates primarily to the sensitivity of the tests. The test should be neither too sensitive so as to give false positive results, nor less than adequately sensitive to give false negative results. Generally speaking, the prior art attempted to solve this problem by mixing the chromogenic agent or agents with certain reducing agents so as to provide the "right" sensitivity to the overall chemical composition used in the tests.
Another problem, which arises in connection with occult blood tests in fecal samples, relates to the manner of handling and processing the aesthetically undesirable specimens. As is evident from the above-cited patents, the prior art attempted to render the handling of stool samples less disagreeable in the laboratory phase of the testing process by providing various sample receiving and storing apparatus.
Still another development in the prior art regarding tests for occult blood in human feces or urine is represented by a test kit sold by Helena Laboratories Corporation of Beaumont, Texas under the CS-T trademark. This test kit comprises a solid testing powder composition containing guaiac derivative as the chromogen, enclosed between two sheets of paper, substantially as is schematically shown on FIGS. 1 and 2 (labeled as "PRIOR ART") of the appended drawings. The kit contains several "bags" or "pouches" of the testing powder composition, and also two bags or pouches of "control" samples, one positive and the other negative, of a second and third powder composition, which is designed to provide color and no color reaction respectively even in the presence or absence of occult blood. The CS-T test kit is usable for "self-testing" by a lay person for detection of occult blood in the stool or urine, by placing the kit into the toilet bowl after a bowel movement. There, the test chemicals located between the two sheets of paper react, in the presence of hemoglobin, to develop an intense color in the test areas where the reactive powder is located.
The present invention represents a still further development in the technological field of test kits for occult blood, particularly of the type which is readily usable by a lay person in a "self-testing" process.